Ammonia synthesis

The Haber–Bosch process revolutionized ammonia production on a global scale. In this Focus issue, we examine the new era of green ammonia synthesis.

Suzanne Zamany Andersen, future founding CEO of Nitrofix Solutions, talks to Nature Synthesis about lithium-mediated ammonia synthesis and a career path through academia and beyond.

Paul Chirik, Edwards S. Sanford Professor of Chemistry at Princeton University, talks to Nature Synthesis about how organometallic catalysis can be used to form weak chemical bonds.

Ammonia synthesis is one of the most important chemical processes as it sustains global food production, but it is a highly polluting and energy-intensive process. Here, the challenges of decarbonizing the process to synthesize green ammonia are discussed.

Green ammonia will play an important function in decarbonized energy systems but its production places a high burden on limited renewable resources in land-constrained countries. Here we propose the offshore production of green ammonia, which can increase energy security without land competition.

Green ammonia synthesis is important for future sustainable manufacturing of fuels and chemicals. This Review highlights the recent progress and challenges in both fundamental research in catalysis and potential industrial scaleup using renewables.

It is challenging to design alloy nanocrystals with complex but homogeneous configurations. Now, a direct solution-phase synthesis is reported which can incorporate different alloy configurations into one nanoparticle. The nanoparticles, with atomically precise catalytic sites, are demonstrated as highly active and cost-effective catalysts.

The conversion of nitrogen (N₂) to ammonia (NH₃) is a key enabler in increasing global food production and nitrogen-containing feedstocks; however, the industrial process for producing NH₃ from atmospheric N₂ is energy intensive and has a large carbon footprint. Now, an efficient and mild catalytic method for the reduction of N₂ has been demonstrated, contributing to the development of a more sustainable process for the production of NH₃.

Well-defined single-atom alloy (SAA) nanocrystals possess isolated atom centres and tunable electronic properties but are challenging to synthesize. Here, a direct solution-phase synthesis of Cu/CuAu core/shell nanocubes with tunable SAA layers is reported. The Cu/CuAu nanomaterial is highly active for the electrocatalytic conversion of nitrate into ammonia.

The synthesis of ammonia from dinitrogen is a vital reaction. Now, ligands prepared based on density functional theory calculations are used with a molybdenum trichloride complex for the production of up to 60,000 equiv. ammonia based on the catalyst, with a molybdenum turnover frequency of 800 equiv. min⁻¹.

Although dinitrogen cleavage by metal complexes is known, the subsequent formation of N–H bonds using H₂ is thermodynamically challenging. Now, ammonia synthesis using an Ir photocatalyst and H₂ for the hydrogenation of a N₂-derived molybdenum nitride is reported. The starting molybdenum nitride can be regenerated to complete a synthetic cycle for the preparation of ammonia from N₂ and H₂.

Ammonia synthesis is of great interest owing to its use in fertilizers and as an energy carrier. However, it is challenging to develop a low-energy catalytic process for the formation of weak N–H bonds. Now, a photocatalytic system harnesses visible light to promote ammonia formation from N₂ and H₂.

Single-atom catalysts (SACs) are attractive for a variety of applications but their synthesis remains challenging. Now, a scalable and economical 3D-printing approach has been developed for producing libraries of SACs using a variety of metals, coordination environments and spatial geometries.

Single-atom catalysts (SACs) can increase atom efficiency and show remarkable catalytic performance compared with their bulk analogues; however, direct fabrication in high yield is challenging. Now, a 3D printing approach realizes the controlled and precise synthesis of SACs with desired geometries.